JP2963931B2 - Vibration barrel polishing of structural ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vibration barrel for a structural ceramic using an abrasive obtained by mixing a medium having a high specific gravity and a free abrasive having a specific particle diameter lower than the specific gravity. This is a vibration barrel polishing method for polishing with a polishing machine.

[Prior Art] Conventionally, the barrel polishing method has been developed for the purpose of deburring metal and surface polishing, but has been subsequently used for polishing a wide range of fields such as plastics, precious stones, glass, and ceramics. The barrel polishing method aims to smooth the surface of the material to be polished, while simultaneously removing sand from the abrasive, deburring the material to be polished, and adding R,
It has the characteristics of mass production and homogenization. Such barrel polishing methods include a rotary barrel polishing method, a dipping barrel polishing method, a centrifugal flow barrel polishing method, and a vibration barrel polishing method. Among them, the polishing of structural ceramics is usually performed by a centrifugal flow barrel polishing method (Japanese Patent Laid-Open No. 58-192745).
No. 1) or a rotary barrel polishing method (Japanese Patent Application Laid-Open No. 60-99555), and it has been considered impossible with the vibration barrel polishing method.

Because the centrifugal flow barrel polishing method and the rotary barrel polishing method flow the workpiece and the abrasive by centrifugal force and rotational force,
This is a method of polishing by relative motion difference due to the flow. In this polishing method, the polishing tank is a closed type, and an even flow of the polishing material and a strong polishing force can be ensured, so that hard structural ceramics can be polished.

On the other hand, the vibration barrel polishing method is a method of polishing by a relative motion difference caused by vibration between a workpiece and an abrasive produced by applying a vibration force. In this polishing method, the upper part of the polishing tank is open, and automation such as sorting can be performed, but the polishing power is weakened, the abrasive sinks down due to vibration, and it is not possible to ensure an even flow, It was said that hard structural ceramics could not be polished.

Further, it is said that it is extremely difficult to grind the structural ceramic with a conventional medium. First, structural ceramics used for cutting tools, cylinders, bearings, etc. are more resistant to impact, abrasion and heat than soft ceramics used for piezoelectric elements, substrates and filters. This is because polishing is difficult. Secondly, since conventionally used media such as alumina are vulnerable to impact, the media itself is only severely worn by loose abrasives. Third, since the conventional media has the same specific gravity as the loose abrasive, the fine abrasive looses to the bottom due to vibration, so that the abrasive does not flow, and the inertia energy is small and no abrasive power is produced. As described above, conventional media have a number of disadvantages, and it has been considered extremely difficult to grind structural ceramics therewith.

"Problems to be Solved by the Invention" For this reason, polishing of structural ceramics is usually performed using a centrifugal flow barrel polishing machine or a rotary barrel polishing machine. In that case, the polishing ability is sufficient because the fluidity of the media is good and the impact force is large, but since the barrel tank is a closed type, the polishing state cannot be checked and the workability is poor, and automation is difficult. However, there is a disadvantage that cracking or chipping is caused by the ceramic polishing. Therefore, in order to easily perform the automation, the polishing state can be confirmed by the upper opening type.
It is desired that the structural ceramics be polished by a vibrating barrel polisher that can be separated from polishing by a single motor. In the case of the vibration barrel polishing, it can be applied to the polishing and deburring of structural ceramics.
Polishing of structural ceramics was not possible due to insufficient polishing capability (FIG. 4). As a result of the observation, the biggest cause of the lack of polishing ability was that the conventional media and the free abrasive material had the same specific gravity, so the fine-grained free abrasive material settled to the bottom due to vibration and did not flow, resulting in the polishing ability It was found that if the size of the free abrasive material was not larger than a certain level, the polishing amount was small, and it was not suitable for use for polishing (FIG. 3).

The present inventor, in order to eliminate such a drawback, when the medium is manufactured with a high specific gravity and mixed with a free abrasive having a low specific gravity and a specific particle size, the free abrasive is pushed upward by vibration. Thus, the ceramics can be made to flow evenly (FIG. 2), and the structural ceramics can be polished by the vibration of the vibrating barrel polishing machine (FIG. 4).

[Means for Solving the Problem] As described above, the present inventor has stated that, in the polishing of structural ceramics by the vibration barrel polishing machine, when the media and the free abrasive have the same specific gravity (specific gravity 3 to 4), Experiments and experience found that loose abrasives settled at the bottom due to vibration and did not flow, resulting in no polishing ability. "As a result of researching to eliminate this, we focused on specific gravity and particle size, and focused on zirconia ( The media is made of high specific gravity material such as ZrO ₂ ) or steel (Fe) whose specific gravity is 6 or more, mixed with free abrasive material with low specific gravity and larger particle size than # 240 to form abrasive material, and these are vibrated. When loaded into the barrel polishing machine and vibrated, it was found that the loose abrasive was pushed upward and could flow evenly with the media, thus completing the present invention.

That is, the first invention to be patented is a vibration barrel in which a workpiece, an abrasive, and water are charged into a polishing tank and vibration is applied to perform polishing by a relative motion difference between the generated abrasive and the workpiece. In the polishing method, the specific gravity of the abrasive is 6
High specific gravity media with lower specific gravity
A vibration barrel polishing method for structural ceramics characterized by being mixed with a free abrasive material comprising alumina (Al ₂ O ₃ ) and / or silicon carbide (SiC) abrasive particles having a particle size larger than 0. It is.

The second invention for which a patent is sought is the method of polishing a structural ceramic for a vibration barrel according to the first invention, wherein a zirconia ball or a steel ball is used as the high specific gravity medium.

[Action] High specific gravity media such as zirconia spheres (ZrO ₂ ) or steel balls (Fe) manufactured using zirconia (specific gravity 6.1) and steel (specific gravity 7.8) have a lower specific gravity (specific gravity 3 to 3).
4) Free abrasive with larger particle size than 240 particle size240Alumina (A
l ₂ O ₃ ) and / or carbon-silicon (SiC) -based abrasive grains when used in combination with high specific gravity media have high inertia energy and high impact and polishing power due to their large mass. (4th
Figure).

The high-density media has a dense and tough inside, so it absorbs the impact of loose abrasives and suppresses wear and breakage of the media.

Since the high specific gravity media pushes the loose abrasive having a low specific gravity upward, it can be made to flow evenly with the media in the barrel tank (FIG. 2).

And so on. As a result, the free abrasive material is caused to continuously collide with the ceramics by using the impact force due to the vibration, and is polished while destroying the ceramics from the generated micro crack surface (FIG. 1).

In addition, the alumina type which can be used as a loose abrasive includes, for example, A (alundum) abrasive grains, WA (white alundum) abrasive grains, HA (single crystal A) abrasive grains, RA abrasive grains, polycrystalline A abrasive grains (TA abrasive grains, 44 abrasive grains), STA (sintered) abrasive grains, and the like are included, and the silicon carbide type includes C, GC (4C), C / GC, A / C, and the like.

"Example" Hereinafter, an example in which a structural ceramic obtained by mixing a high specific gravity medium and a low specific gravity free abrasive material and subjected to vibration barrel polishing will be described.

<Example 1> In a polishing tank, zirconia and alumina were prepared as a work material as a workpiece, zirconia spheres were prepared as a medium, and an alumina (WA abrasive) having a grain size of 120 was used as a free abrasive. And / or silicon carbide (C abrasive grains, GC abrasive grains) -based abrasive grains with an abrasive quantity of 1, in addition to these compounds
And 15cm ^3, was charged with water of 700 cm ^3, was polished by applying vibration for 3 hours. As a result, as shown in FIG. 5, it was found that both the work materials were polished. In particular, alumina shows a large polishing amount.
At the same time, polishing of the steel ball (Fe) was also performed, but the polishing amount of the softer steel ball is smaller than that of the ceramic. From this, in the vibration barrel polishing, a mechanism of polishing while finely crushing a workpiece by vibration with a medium and a free abrasive material is considered. Therefore, a material that is easily broken, such as alumina, requires a large amount of polishing, and a material having relatively high toughness, such as zirconia, requires a small amount of polishing. Since the steel balls are particularly sticky, the polishing amount is smaller than that of zirconia.

As for the type of loose abrasive, the polishing amount of C abrasive grains and GC abrasive grains is large, and the polishing amount of alumina abrasive grains is small. As for the surface roughness, C abrasive grains having high toughness tend to be large. Sixth
The figure is a graph showing the relationship between the type of loose abrasive and the surface roughness curve.

<Example 2> In a polishing tank, zirconia and alumina were prepared as workpieces, and zirconia spheres were used as a medium, and silicon carbide (GC abrasive) -based abrasive grains were used as a free abrasive.
No. 60, a particle size # 120 No., size # 240 No., and prepared granularity # 2500 No. alumina (WA abrasive grains) abrasive particles, the abrasive grain weight 1, 15cm ³ A compound, instrumentation and water of 700 cm ³ And polished by applying vibration for 3 hours. As a result, as shown in FIGS. 7 and 8, it was found that both the workpieces were polished to a satisfactory degree of polishing and surface roughness. In particular, the purpose of this experiment is to examine mainly the relationship between the particle size, the polishing amount, and the surface roughness. When polished for 3 hours, the relationship between the polished amount and the surface roughness does not change much for particle sizes # 60 to # 240. However, in the initial stage (1 hour polishing), the larger the particle size, the larger the polishing amount and the surface roughness. 7 and 8 also show the particle size # 2500 as a reference experiment example. In the case of the particle size # 2500, the surface roughness is small, but the polishing amount is also small.
It turns out that it is not suitable for use.

<Example 3> In a polishing tank, zirconia and alumina were prepared as workpieces, and zirconia spheres were used as a medium, and silicon carbide (C abrasive) -based abrasives were used as free abrasives.
1, 1 and 2 l were prepared. In addition to these, 15 cm ³ and 700 cm ³ of water were charged as a compound, and polished by applying vibration for 3 hours. As a result, the ninth
As shown in FIG. 10 and FIG. 10, it was found that both the zirconia and the alumina increased the polishing amount and the surface roughness as the amount of free abrasive increased.

<Example 4> In a polishing tank, zirconia, alumina, and silicon nitride were prepared as workpieces as workpieces, zirconia spheres were used as a medium, and silicon carbide (GC) having a grain size of # 120 was used as a free abrasive. A / C abrasive grain) was prepared, and in addition to these, 150 cm ³ and a water amount of 700 cm ³ were charged as a compound and polished by applying vibration for 3 hours. As a result, as shown in FIGS. 11 and 12, the polishing amount increases as the polishing time elapses, and the surface roughness decreases.
However, after 3 hours, the free abrasive material is atomized by crushing, so that the polishing amount decreases except for Fe.

<Example 5> In a polishing tank, zirconia and alumina were prepared as workpieces as workpieces, zirconia balls and steel balls were used as media, and silicon carbide (GC) having a grain size of # 120 was used as a free abrasive. 1) Abrasive grains are prepared, and in addition to these, 15 cm ³ and 700 cm ³ of water are charged as a compound.
Polishing was performed by applying vibration over time. As a result, as shown in FIG. 13, it was found that the steel ball media softer than the zirconia ball media had a larger polishing amount. In the method using the steel ball media, since the impact is given to the workpiece while the loose abrasive is held by the soft base material, the polishing amount is considered to be larger than the zirconia ball media. FIG. 14 is a surface roughness curve due to the difference in media, and shows that the steel ball media has a surface roughness more than twice as large and is sharp.

When a steel ball is used, a compound may be added if necessary. This compound causes lubrication, cleaning, rust prevention, and cooling, and it has been found that the amount of polishing and the surface roughness vary depending on the type of the compound.

"Effects" As described above, the invention of the present application has developed a high-density medium for polishing a sintered body of structural ceramics, which was conventionally only polished with a centrifugal flow barrel polishing machine, and has a lower specific gravity and a moderate density. Is mixed with a free abrasive having a particle size of, and charged into a vibrating barrel polishing machine, and by applying vibration, polishing is performed by a relative motion difference between the generated abrasive and the workpiece, whereby centrifugation is performed. Polishing can be performed with an efficiency equal to or higher than the polishing ability of a fluid barrel polishing machine or a rotary barrel polishing machine. In other words, the present invention has enabled highly efficient polishing of structural ceramics by the vibration barrel polishing method, which has been conventionally difficult.

In addition, centrifugal flow barrel polishing and rotary barrel polishing are excellent in polishing power and can be polished even for structural ceramics, but if the polishing tank for centrifugal flow or rotation is an open top type, the stored items will be scattered. Inevitably, it must be closed (batch type). For this reason, it is impossible to sort media and workpieces, and automation and continuous operation are difficult. On the other hand, the vibrating barrel machine can be of an open top type because the medium and the workpiece only flow due to vibration and do not jump out. As a result, in the vibrating barrel machine, since the sorting of the media and the workpiece can be easily performed by the sorting line, automation and continuous operation are possible. In other words, the development of the vibration barrel polishing method for structural ceramics according to the present invention has made it possible to easily perform continuous and automatic polishing of structural ceramics, which was conventionally difficult.

[Brief description of the drawings]

FIG. 1 is a diagram showing a vibration barrel polishing mechanism for ceramics using a high specific gravity medium and a loose abrasive, FIGS. 2 and 3 are flow mechanism diagrams in the vibration barrel polishing of a medium and a loose abrasive, and FIG. , Indicating that the high specific gravity media can push up the loose abrasive with low specific gravity to the upper part and make it flow evenly, enabling the polishing of ceramics.
FIG. 3 shows a state in which the fine abrasive particles sink to the bottom due to vibration and no longer flow because the conventional media and the loose abrasive have the same specific gravity. A graph showing the polishing amount of (alumina),
FIG. 5 is a graph showing the relationship between the type of loose abrasive and the amount of polishing and surface roughness, FIG. 6 is a curve showing the type of loose abrasive and surface roughness, and FIG. FIG. 8 is a graph showing the relationship between the type of particle size and the surface roughness, and FIG. 9 is a graph showing the relationship between the amount of the free abrasive and the polishing amount and the surface roughness. 10 is a curve showing the amount of free abrasive and surface roughness, FIG. 11 is a graph showing the relationship between the polishing time and the amount of polishing and surface roughness, FIG. 12 is a curve showing the polishing time and surface roughness, FIG. 13 is a graph showing the relationship between the polishing amount and the surface roughness depending on the media, and FIG. 14 is a surface roughness curve depending on the media.

Claims (2)

(57) [Claims] 1. A vibration barrel polishing method in which at least a workpiece, an abrasive, and water are charged into a polishing tank and vibration is applied to perform polishing by a relative motion difference between the generated abrasive and the workpiece. A high specific gravity medium having a specific gravity of 6 or more and a free abrasive material composed of alumina-based and / or silicon carbide-based abrasive particles having a lower specific gravity and a larger particle size than # 240 are used. Vibration barrel polishing method for structural ceramics. 2. The method according to claim 1, wherein a zirconia ball or a steel ball is used as the high specific gravity medium.